Late 40s / Early 50s René Herse tip find

[Guinessisgoodforyou]

Thanks for those. Hmm, there’s not much difference between the 23mm and 23.3/23.4mm sizes then. I’ll have to see if I can find a thread pitch set to check a bit more closely so I don’t end up with the wrong one. I’m just checking with a pal in case his crank extractor is double-sided like the VAR one you linked to.

The .1mm over the diameter should make no difference. It's only .05mm from root to crest. The pitch error will be obvious if the threads are clean and the extractor doesn't screw in with your fingers.

 

[Jonny69]

The .1mm over the diameter should make no difference. It's only .05mm from root to crest. The pitch error will be obvious if the threads are clean and the extractor doesn't screw in with your fingers.

I wasn’t worried about the 0.1mm difference between 23.3 and 23.4. Like you say, that’ll just get lost in the noise. I was thinking more along the lines that if my pal has a 23mm extractor it should be obvious if my cranks are threaded with 23mm or 23.3/23.4mm because it’ll either be very loose in the threads or it’ll fit snugly. I think the fact that the ID measures up below 22mm and the pitch is about 1mm, logic to me says it’s probably more likely to be 23mm than the bigger one anyway

 

[Woz]

I'll put this out which I've had bookmarked in case it helps. It's in French, but lot's of pictures and fairly obvious how it works.

https://www.muzarde.com/fabriquer-un-extracteur-universel-de-manivelles-a-axe-carre/

It's interesting, because it mimics something I've seen in a vintage VAR catalogue



In one picture, he show's it with a RH crank amongst others.

 

[Woz]

There is reference to a RH crank removal tool here (but no details):

http://www.blackbirdsf.org/herse/

 

[Jonny69]

https://www.muzarde.com/fabriquer-un-extracteur-universel-de-manivelles-a-axe-carre/

It's interesting…

No, that is really interesting. If I can’t get the crank off with an ordinary puller and a bit of heat, I reckon I can definitely make something like that with a yoke that won’t damage the back of the crank.

There is reference to a RH crank removal tool here (but no details):

http://www.blackbirdsf.org/herse/

Great resource!

 

[Jonny69]

The bottom bracket I’m less worried about. I have a decent hook wrench for the lock ring and if my usual Park Tool pin wrench won’t turn the cup I’ve got this monster adjustable one with a bag full of different size pins, that I used to hammer the lock rings free in the rear hubs of my Citroen Ami. Brown 1980s multimeter for scale.

 

[Woz]

- while we don't know each other, how you are setting about this bike, and a bit of Fluke test equipment I'm sure the end will be rosey.

I know nothing about cars. But I have one, and a fcuking money pit compared to my velos.

For the BB. The right side DS cup is potentially a sacred installation. The Pope may have been involved for what it's worth.

If you not confident in tooling, and don't see overall benefits to take out the DS cup, leave it be would be my recommendation.

I can promise, you won't be the first nor the last that this is a big sticking point with French bikes.

 

[dirttorpedo]

Freaking amazing find. I'm interested in seeing how things go.

 

[Jonny69]

No progress since the last update, unfortunately. I took the nds crank into work to measure the thread more accurately (and to see if I had anything that would go over the pedal flats) but I kept pushing it to the back of the queue because work has been mad for the last couple of months. I should be able to have a look next week and hopefully make some fresh progress

 

[Jonny69]

Done some measuring on that crank. ID of the thread is 21.9mm across various places. I put a 1mm thread gauge in to measure the pitch but none of us had eyes good enough to see if it was actually seating in the threads. Equally unclear with the 0.9mm and the 1.1mm but it definitely felt like it wasn't seating with the 1.2mm.

Double checked in the stash of taps and we had an M22x1 and an M24x1 but not an M23x1 - typical!

Then we got technical. Down at our workshop there's an optical measuring machine like this one:



We got a bit of plasticine and pushed it into the thread, then lined it up in front of the camera and measured across the peaks. Measured between 0.9mm, 1mm and 1.1mm depending which thread peak you used, because they weren't perfect, but it's definitely not as big as 1.3mm. So I'm fairly confident that points to it being M23x1 and not the bigger 23.3mm-23.4mm thread. I've ordered up the 23mm VAR puller from HubJub as recommended by @Guinessisgoodforyou